Cascode multivibrator



Jan 22, 1957 R. l, RoPlEQUE-r cAscoDE MumIVIBRATORy Filed Aug. 18, 1953 United States Patent O CAscoDE MULTrvIBRAToR Richard L. Ropiequet, Portland, Oreg., assignor to Tektronix, Inc., Portland, Greg., a corporation of regon Application August 1S, 1953, Serial No. 374,959

16 Claims. (Cl. Z50-Z7) This invention relates to trigger circuits of the multivibrator type, and relates particularly to the novel construction of a multivibrator circuit which affords greater band width of operation and faster transition time than provided heretofore.

It is the principal object of this invention to provide a multivibrator which utilizes triodes in cascode and affords triggering at higher frequencies than provided heretofore.

Another important object of the present invention is to provide a multivibrator circuit in which `the transition time is shortened substantially, whereby to reduce the operat ing time cycle.

A further important object of this invention is the provision of a multivibrator circuit which utilizes two pairs of triodes each arranged in cascode for bistable operation.

A still further important object of this invention is the provision of a multivibrator having a very precise level of triggering potential.

These and other objects and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawing in which;

Figure l is a schematic diagram of aV preferred form of multivibrator circuit embodying the features of the present invention;

Figure 2 is a schematic diagram of a modified form of multivibrator circuit embodying features of the present invention; and I Figure 3 is a schematic diagram of a still further modied form of multivibrator circuit embodying features of this invention.

In its broad aspect, the multivibrator of the present invention involves the arrangement of a pair of triode elements wherein the plate of one triode and the cathode of the other triode are connected together and the trigger signal is direct coupled to said connection.

The multivibrator shown .in Figure 1 comprises four triodes V1, V2, V3 and V4. The plate 10 and cathode 11 of tubes V1 and V2, respectively, are connected together, as are the plate 12 and cathode 13 of the respec- 2,778,935 Patented Jan. 22, 1957 the plate 16 of V2, for purposes to be explained in detail hereinafter. As shown in the drawing, the cathode 30 of tube V is connected in the circuit adjacent the resistance 28, and the grid 31 of said tube is connected through resistance 32 to the plate 16 of tube V2. Thev plate 33 of the cathode follower tube V5 is connected to a positive potential, for example 350 volts, as shown.

A particular feature of the present invention resides in the direct coupling of a positive trigger pulse`34, employed to trigger the multivibrator, at the junction 35 rof the cathode 11 of V2 and the plate 10 of V1. Cathode a positive potential, as shown.

tive tubes V4 and V3. The cathodes 14 and 15 of tubes V1 and V4 are grounded, and the plates 16 and 17 of the tubes V2 and V3, respectively, are connected through the respective resistances 18 and 19 to a positive potential, for example +225 volts, as shown. f The grids 20 and 21 of the respective tubes V2 and V3 are connected to a positive potential of, for example, 100 volts.

The grid 22 of tube V1 is connected through resistance 23 to a negative potential of, for example, -150 Volts and is also connected through the parallel combination of resistance 24 and capacitor 25 to the plate 17 of tube V3.

In similar manner, the grid 26 of tube V4 is connected through resistance 27 to the negative potential and also through the parallel combination of resistance 28 and capacitor 29 to the plate 16 of tube V2. In this latter instance, however, it is preferred that the cathode vfollower tube VS be used to couple the grid 26 of V4 and In similar manner, cathode follower tube V7 is employed to connect a trigger or reverting pulse to the rightside of the multivibrator at junction 40 between the cathode 13 and the plate 12 .of lthe respective tubes V3 and V4. The cathode 41 of tube V7 is connected to said junction 40, the plate 42 is connected to a positive potential and the grid 43 is connected to terminal 44, at which is applied the triggering or reverting pulse.

The operation of the multivibrator described hereinbefore is as follows: The left hand side (V1 and V2) of the multivibrator is normally conducting. A positive trigger pulse 34 applied to the grid 37 of the cathode follower V6 causes the latter to divert current from tube V2 so that the plate 16 rises -in potential. The resulting positive step at this plate is coupled through cathode follower V5 to the grid 26 of the opposite lower tube V4. Thus, the multivibrator ops over, with conduction on the right side.

Cathode follower V5 functions as a buffer between the plate 16 of V2 and all other external loads. Thus, the only additional capacitance presented is the input capacitance of the cathode follower itself. The plate 16 of V2 is thus permitted to rise in potential at a much higher rate of speed than otherwise aiforded.

' The multivibrator described hereinbefore may be utilized for many purposes, such as in electronic counters and other instruments wherein trigger circuits are employed. It is particularly adapted for use in the cathoderay oscilloscope for production of the time base. For such purpose the plate 17 of V3 is connected by terminal 45 to a sawtooth time base generator (not shown). The negative-going waveform provided at the right side of the multivibrator activates the sawtooth generator. It is convenient to couple the sawtooth generator back to the multivibrator junction 40 .through cathode follower V7, by connection to terminal 44, so that the sawtooth sweep voltage itself may function upon reaching a desired level of potential to raise the potential of the grip 43 of the cathode follower V7 to a value at which this tube will divert current from the upper right tube V3 of the multivibrator and thereby effect reversion of the multivibrator to its initial stage, i. e. with the left hand side conducting.

A particular advantage of the multivibrator circuit described hereinbefore resides in the manner in which the trigger signal is introduced to the multivibrator. The points of injection 35 and 40 for the left and right sides, respectively, present a very low impedance when the corresponding side of the multivibrator is conducting. Accordingly, these points have very Wide band width and thereby provide for the use of trigger signals of much higher frequency than heretofore permitted.

A further important advantage of the multivibrator circuit described hereinbefore resides in the use of cathode followers for introducing the trigger or reverting signal at the points 3S and 40, respectively. Since the cathode follower is characteristically of wide bandwidth, the trigger signal is not o nly introduced at the most efficient point but also the 'total responseV of the multivibrator is .greatly improved since the other points 'in the niultivibratorare not loaded down with the trigger signal.

.It will be apparent from the foregoing that the multivibrator illustrated in Figure l is stable in both directions, i. e. a trigger signal is required to be impressed at junction 35 to cause the multivibrator to flop over anda trigger signal is also required to -be impressed at junction 40 to cause .the multivibrator to revert to its initial state. The advantages of the present invention may also be realized with various other types of muitivibrator circuits, for example the monostable circuits illustrated in Figures 2 and 3.

In Figure 2 of .the drawing the multivibrator is shown to comprise the two pairs of triodes 'VL'VZ and V3, V4 arranged in the cascode conguration of Figure 1, with the exception that the gridlZZ of tube V1 and the plate 17y of tube V3 are coupled together by means of capacitor 50 and grid 22 is also Aconnected to a positive potential through resistance 51. The capacitor E@ and resistance 51 form an RC network which determines the time cycle of operation of the multivibrator and therefore the reverting signal coupled to junction 40 in the modification of Figure v1 is not required.

In the modification illustrated in Figure 3 of the drawing, the pentode tube V8 is substituted for the cascode arrangement of tubes V3 and V4 utilized in the multivibrator circuits illustrated in Figures l and 2. The cathode 60 is connected to ground and the screen grid 61 is connected to a positive potential. The suppressor grid 62. is provided with terminal 63 by means of rwhich a negative signal 64 may be introduced to the right hand side of the multivibrator for purposes of reverting the latter. The plate 65 is connected through ,the parallel combination of resistance 66 and capacitor 67 to the grid 22 of tube V1, while the controlgrid 68 is connected through the parallel combination of resistance 69 and capacitor 70 tothe plate 1 6 of tube V2. The grid 22 of tube V1 is connected through resistance 71 to a negative potential and grid 63 of tube VS is connected through resistance 72 to a negative potential, in the manner of the modificationshown,y in Figure 1.

It will be `noted that in both ofthe modiiications shownv in Figures?. and 3, the trigger signal 34 Ais impressed upon the multivibratoratthe casfcode junction 3S, inthe manner of the modification shown in Figure 1. Thus the modications areeachp-providcd with a trigger injection point at very wideband width, as er.- plained hereinbefore. Although the modifications of Figures 2 and 3 are illustrated insimplest form, it will be understood that various changes may be made therein, For example the cathode follower V shown in Figure 1 may be utilized in the plate circuit 16 of tubes V2 in the modifications of Figures 2 and 3 to provide the advantages of operation described hereinbefore. Further, the circuit arrangement of Figure 3 may be modied to provide the RC network of Figure 2, in inanner well-known to those skilled in the art.

It will be apparent to those skilled in the art that various other changes in details of construction of the multivibrator circuit of the present invention may also be made withoutdeparting from the scope and spirit of this invention. Accordingly, it is to be understood that the foregoing description is merely illustrative of the vention and is not to be considered in a limiting sense.

Having new described my invention and the manner in which the same may be used, what l claim as new and desire to secure by Letters Patent is:

l. A trigger-actuated multivibrator comprising a plu rality of electron discharge devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, one side of the multivibrator comprising a pair of electron discharge devices, the cathode of one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, means connecting the plate of the said one electron discharge device of the pair and the grid of the said other electron discharge device of the pair to the other side of the multivibrator, the remaining elements of each electron discharge device being connected to a source of operating potential, and signal conductor means connecting a triggering signal to the said cathode-plate connection.

2. A trigger-actuated multivibrator comprising a plurality of electron discharge devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, one side of the multivibrator comprising a pair of electron discharge devices, the cathode of one electron discharge device'of the pair lbeing conne'cted to the plate of the other electron discharge device of the pair, means connecting the plate of the said one electron discharge device of the pair and the `grid of the said other electron discharge device of the pair to the other side of the multivibrator, the remaining ele- `ments of each electron discharge device being connected to a source of operating potential, and cathode follower means connecting a triggering signal to the said cathodeplate connection.

3. A trigger-actuated multivibrator comprising a plurality of electron discharge devices arranged vin a normally conducting'side and a normally Anon-conducting side, each electron discharge device having cathode, grid and plate elements, -one side of the multivibrator cornprising a pair of electron discharge devices, the cathode of one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, cathode follower means connecting the plate of the said one electron discharge device of the pair to a grid of the other side of the multivibrator, means connecting the grid of said other electron discharge device of the pair to a plate of the other side of the multivibrator, the remaining elements of each electron discharge device being connected to a source of operating potential, and cathode follower means connecting a triggering signal to the said cathode-plate connection.

4. A trigger-actuated multivibrator comprising a plurality of electron discharge'devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, the normally conducting side of the multivibrator comprising a pair of electron discharge devices, the cathode of'one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, means connecting the plate of the said one electron discharge device of the pair and the grid of the said other electron discharge device of the pair to the grid and plate, respectively, of the normally nonconducting side of the multivibrator, the remaining elements of each electron discharge device being connected to a source of operating potential, and signal conductor means connecting a triggering signal to the said cathodeplate connection.

5. A trigger-actuated multivibrator comprising a plurality of electron discharge devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, the normally conducting side of the multivibrator comprising a pair of electron discharge devices, the cathode of one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, means connecting the plate of the said one electron discharge device of the pair and the grid of the said other electron discharge device of the pair to the grid and plate, respectively, of the normally non-conducting side of the multivibrator', the remaining elements of each electron discharge device being connected to a source of operating potential, and cathode follower means connecting a triggering signal to the said cathodeplate connection.

6. A trigger-actuated multivibrator comprising a plurality of electron discharge devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, the normally conducting side of the multivibrator comprising a pair of electron discharge devices, the cathode of one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, cathode follower means connecting the plate of the said one electron discharge device of the pair to a grid of the normally non-conducting side of the multivibrator, means connecting the grid of the said other electron discharge device of the pair to a plate of the normally non-conducting side of the multivibrator, the remaining elements of each electron discharge device being connected to a source of operating potential, and cathode follower means connecting the triggering signal to the said cathode-plate connection.

7. A trigger-actuated multivibrator comprising a plurality of electron discharge devices arranged in a normally conducting side and a normally non-conducting side, each electron discharge device having cathode, grid and plate elements, the normally nonconducting side of the multivibrator comprising a pair of electron discharge devices, the cathode of one electron discharge device of the pair being connected to the plate of the other electron discharge device of the pair, means connecting the plate of the said one electron discharge device of the pair and the grid of the said other electron discharge device of the pair to the grid and plate, respectively, of the normally conducting side of the multivibrator, the remaining elements of each electron discharge device being connected to a source of operating potential, and signal conductor means connecting a triggering signal to the said cathodeplate connection.

8. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, the grid of one electron discharge device of one pair being connected to the plate of a different electron discharge device of the other pair, the remaining elements of each electron discharge device being connected to a source of operating potential, and signal conductor means connecting a triggering signal to the cathode-plate connection of at least one pair of electron discharge devices.

9. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, the grid of one electron discharge device of one pair being connected to the plate of a different electron discharge device of the other pair, the remaining elements of each electron discharge device being connected to a source of operating potential, and cathode follower means for introducing a triggering signal to the cathode-plate connection of at least one pair of electron discharge devices.

10. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, one pair being normally conducting and the other pair being normally non-conducting, the grid of one electron discharge device of one pair being connected to the plate of a diterent electron discharge device of the other pair, the remaining elements of each electron discharge device being connected to a source of loperating potential, and cathode follower means for introducing a triggering signal to the cathode-plate connection of the normally conducting pair of electron discharge devices.

l1. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having a cathode, a grid and a plate, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, the grid of one electron discharge device of one pair being connected to the plate of a diierent electron discharge device of the other pair, means for introducing a triggering signal to the cathode-plate connection of at least one pair of electron discharge devices, resistance means connecting the grids of the electron discharge devices having plate-connected grids to a negative potential, means connecting the cathodes of the electron discharge devices having plate-connected grids to ground, and means connecting the plate and grid of each of the remaining electron discharge devices to a positive potential.

l2. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having a cathode, a grid and a plate, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, one pair being normally conducting and the other pair being normally non-conducting, the grid of one electron discharge device of one pair being connected to the plate of a diierent electron discharge device of the other pair, cathode follower means for introducing a triggering signal to the cathode-plate connection of the normally conducting pair of electron discharge devices, means connecting the grids of the electron discharge devices having plate-connected grids to a negative potential, means connecting the cathodes of the electron discharge devices having plateconnected grids to ground, and means connecting the plate and grid of each of the remaining electron discharge devices to a positive potential.

13. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, the grid of one electron discharge device of one pair being connected to the plate of a different electron discharge device of the other pair, cathode follower means in one of the said grid-to-plate connections, the remaining elements of each electron discharge device being connected to a source of operating potential, and means for introducing a triggering signal to the cathode-plate connection of at least one pair of electron discharge devices.

14. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, one pair being normally conducting and the other pair being normally non-conducting, the grid of one electron discharge device of one pair being connected to the plate of a different electron discharge device of the other pair, cathode follower means in the connection between the grid of the normally non-conducting pair of electron discharge devices and the plate of the normally conducting pair of electron discharge devices, the remaining elements of each electron discharge device being connected to a source of operating potential, and means for introducing a triggering signal to the cathode-plate connection of at least one pair of electron discharge devices.

l5. A trigger-actuated multivibrator comprising two pairs of electron discharge devices each having cathode, grid and plate elements, the cathode of one electron discharge device of each pair being connected to the plate of the other electron discharge device of each pair, one pair being normally conducting and the other pair being normally non-conducting, the grid of one electron discharge device of one pair being connected to the plate of af differentA electron discharge device of the other, pair, cathode follower means n in theY connection betweenihe grid of the normally non-conducting pair of,electro;n.dis charge devices and the plate of the normally conducting pair ofuelectron dischargeI devices, the remaining elements of each electron discharge device being connected to a source of koperating potential, and cathode follower means for introducing a triggering signal tothe cathode-plate connection of the normally conducting pair of electron discharge devices.

16. A` trigger-actuated multivibrator comprising two pairs of electron discharge devices each having a cathode, agrid and a plate, the cathode of one electron discharge device of each pairI b eing connected to the plate of the other electron discharge .device Aof leach pair, one pair being normally conducting and the. other pair beingnorrnally non-conducting, the grid of onel electron discharge device of one pair being connected to the plate of a different electron discharge device of the` other pair, cathode` follower means iny the connection between the grid ofthe normallyv 11on-conhicting pairV of the electron discharge devicesanqthe platetofthe ncrmally Conducting nairof electron discharge devices, cathode follower means for introducing a triggering lsignal/to the cathode-,plate c onnection of at least one pair of electron dischargeV devices, resistance lmeans coizrniectiigtg the grids of the electrondischarge devices having plate-connected grids to a negative potential, means connecting the cathodes ofthe electron discharge deviceshaving plate-connected grids to ground, and means connectingthe plate, and grid of each of the remainingv electron discharge devices to positive potentials.

References Cited in the vfile of this patent UNITED STATESPATENTS 2,494,357 Rogers Jan. 10, 1950 2,540,539 Moore Feb. 6, 1951 2,550,116 Grosdoff Apr. 24, y1951 2,562,530 Dickinson July 31, 1951 2,577,074 Dickinson Dec. 4, 1951 2,750,502 Gray June 12, 1956 

